Color mode changes when opening .ai file in Photoshop?

When opening an Illustrator file in Photoshop, the Import PDF dialog box opens, as shown in the picture below. It says Import PDF because the Illustrator file format is based on Adobe PDF.

The Mode menu sets the color mode of the converted file, so it’s important for whoever is opening the AI file in Photoshop to pay attention to the Mode menu when converting. In the example above, sRGB is currently checked (red) because the Illustrator file’s color mode is RGB. CMYK is being selected (green) to make sure that will be the color mode of the converted file. When I tested this, if the Illustrator file is CMYK, that Mode menu defaults to CMYK. So if they open your Illustrator file and that Mode menu comes up RGB, that means that Illustrator document was actually saved in RGB color mode.

It’s also important to note that Photoshop converts the Illustrator file to CMYK specifically using the CMYK profile currently selected in Edit > Color Settings. Whoever is doing the conversion should make sure that in advance, in Photoshop Color Settings, the CMYK working space profile is set to use the ICC profile that represents the printing conditions of their press.

If they don’t do that, then for example if Photoshop Color Settings is currently set to a CMYK profile such as U.S. Web Coated SWOP, and their printer is using a press setup that is nothing like that, then Photoshop will be applying an incorrect CMYK conversion.

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@sydneybrookehughes wrote:

My blues printed purple.

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CMYK is only capable of reproducing such a narrow range of blues that great care should be taken to make sure you are specifying blues that can actually be printed in CMYK. Blues shifting to purple is often a symptom that the original file was actually edited using the much wider range of blues in RGB, then on CMYK conversion those blues end up shifted into the range the inks can cover. Depending on which blue it is, that can result in different blues, darker blues, or purple.

Some things to look at there:

First make sure your Illustrator document was actually edited in CMYK; in Illustrator check File > Document Mode.

In Illustrator choose Edit > Color Settings and make sure the printer’s press profile is selected under Working Spaces: CMYK. That takes care of the application’s default profile.

Then, to take care of the current document’s profile: choose Edit > Assign Profile, and if Working CMYK isn’t already set to the printer’s press profile, change it in the Profile list. If this alters colors, correct them now that it’s being displayed through the correct profile.